Method for real time update of fly-through camera placement

ABSTRACT

A virtual endoscopic view shows a surgical area and surrounding anatomy and may also show a position of a surgical instrument in use during a surgical procedure, allowing a surgeon to virtually view the surgical area when direct viewing or actual endoscopic views are incomplete, obstructed, or otherwise unavailable or undesirable. In order to render the endoscopic view, an IGS navigation system may be configured with an observer point and an observer orientation within 3-D space based upon user inputs. A user interface for defining these points allows a user to view a virtual endoscopic preview in real-time while providing inputs, thus improving the likelihood that the resulting virtual endoscopic view is as desired by the user; and reducing time spent redefining and reconfiguring the virtual endoscopic view. The virtual endoscopic preview may provide combinations of static and dynamic images to illustrate the spatial relationship of the provided inputs.

PRIORITY

This application claims priority to U.S. Provisional Patent 62/748,571,filed Oct. 22, 2018 and entitled Method for Real Time Update ofFly-Through Camera Placement, the disclosure of which is incorporated byreference herein.

BACKGROUND

Image-guided surgery (IGS) is a technique where a computer is used toobtain a real-time correlation of the location of an instrument that hasbeen inserted into a patient's body to a set of preoperatively obtainedimages (e.g., a CT or MRI scan, 3-D map, etc.), such that the computersystem may superimpose the current location of the instrument on thepreoperatively obtained images. An example of an electromagnetic IGSnavigation systems that may be used in IGS procedures is the CARTO® 3System by Biosense-Webster, Inc., of Irvine, Calif. In some IGSprocedures, a digital tomographic scan (e.g., CT or MM, 3-D map, etc.)of the operative field is obtained prior to surgery. A speciallyprogrammed computer is then used to convert the digital tomographic scandata into a digital map. During surgery, special instruments havingsensors (e.g., electromagnetic coils that emit electromagnetic fieldsand/or are responsive to externally generated electromagnetic fields)are used to perform the procedure while the sensors send data to thecomputer indicating the current position of each surgical instrument.The computer correlates the data it receives from the sensors with thedigital map that was created from the preoperative tomographic scan. Thetomographic scan images are displayed on a video monitor along with anindicator (e.g., crosshairs or an illuminated dot, etc.) showing thereal-time position of each surgical instrument relative to theanatomical structures shown in the scan images. The surgeon is thus ableto know the precise position of each sensor-equipped instrument byviewing the video monitor even if the surgeon is unable to directlyvisualize the instrument itself at its current location within the body.

In order to provide the virtual endoscopic view described above, the IGSnavigation system may require “placement” of a virtual “camera” todefine the viewpoint presented by the virtual endoscopic view. Suchplacement may require configurations or inputs defining an observerpoint (i.e., a point along an x, y, and z-axis in 3-D space at which aviewer of the virtual endoscopic view is located) and an observerorientation (i.e., Euler angles defining a direction in 3-D space thatthe viewer is facing). Defining locations and orientations in virtual3-D space can be difficult when using conventional 2D interfaces andtools instead of 3-D capable interfaces and tools.

As an example illustrating the potential difficulty, when using 3-Dinterfaces and tools, such as a virtual reality head mounted displaythat is capable of room-scale movement and viewing of a 3-D virtualenvironment with six degrees of freedom, placement of the virtual cameracan be as simple as walking around or using a controller to move withinthe virtual 3-D space (i.e., moving along the x, y, and z axis) and thenlooking in the desired direction (i.e., rotating yaw, pitch, and roll).

When using 2D interfaces, such as a computer display and a mouse,navigating and viewing the same 3-D virtual environment in order todefine an observer point and orientation may be less intuitive and moreerror prone. Conventional 2D interfaces may require a user to browsethrough a number of individual images of the digital map using akeyboard and mouse, and then manually select a point on a first image aseither the observer location or orientation, and then select a point ona second image as the remaining point. The first image and the secondimage might not fall on the same point in the Z-axis (i.e., the thirddimension), making it difficult to judge their relation to each other asa 2D observer. As a result, the process of configuring virtualendoscopic views during IGS navigation can be inaccurate (e.g., a usermay select the first and second point and then decide after the virtualendoscopic view is rendered that it is not what was desired) andinefficient (e.g., a user may need to re-define the first and secondpoint a number of times in order to achieve the desired perspective).

Such inaccuracy and inefficiency can have a negative impact on outcomesof a surgical procedure, including reducing the quality or availabilityof viewpoints available through the endoscopic view, and increasing theoverall time required to complete the procedure. Thus, it may beadvantageous to provide an IGS navigation system with improved featuresfor defining viewpoints and perspectives within a virtual endoscopicview.

While several systems and methods have been made and used in surgicalprocedures, it is believed that no one prior to the inventors has madeor used the invention described in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims which particularly pointout and distinctly claim the invention, it is believed the presentinvention will be better understood from the following description ofcertain examples taken in conjunction with the accompanying drawings, inwhich like reference numerals identify the same elements and in which:

FIG. 1 depicts a schematic view of an exemplary surgery navigationsystem being used on a patient seated in an exemplary medical procedurechair;

FIG. 2 shows an exemplary set of high level steps that may be performedby or with the surgery navigation system of FIG. 1 to place a virtualcamera;

FIG. 3 shows an exemplary set of steps that may be performed by or withthe surgery navigation system to provide a real-time virtual endoscopicpreview during placement of a virtual camera;

FIG. 4 shows an exemplary set of steps that may be performed by or withthe surgery navigation system to review, modify, and confirm placementof a virtual camera;

FIG. 5 shows a simulated screenshot of an exemplary placement interface;

FIG. 6 shows a simulated screenshot of the placement interface of FIG. 5providing a first preview;

FIG. 7 shows a simulated screenshot of the placement interface of FIG. 5providing a second preview;

FIG. 8 shows a simulated screenshot of the placement interface of FIG. 5providing a third preview;

FIG. 9 shows a simulated screenshot of the placement interface of FIG. 5providing a fourth preview;

FIG. 10 shows a simulated screenshot of an alternate exemplary placementinterface providing a first preview;

FIG. 11 shows a simulated screenshot of the alternate placementinterface of FIG. 10 providing a second preview;

FIG. 12 shows a simulated screenshot of the alternate placementinterface of FIG. 10 providing a third preview; and

FIG. 13 shows a simulated screenshot of the alternate placementinterface of FIG. 10 providing a fourth preview.

The drawings are not intended to be limiting in any way, and it iscontemplated that various embodiments of the invention may be carriedout in a variety of other ways, including those not necessarily depictedin the drawings. The accompanying drawings incorporated in and forming apart of the specification illustrate several aspects of the presentinvention, and together with the description serve to explain theprinciples of the invention; it being understood, however, that thisinvention is not limited to the precise arrangements shown.

DETAILED DESCRIPTION

The following description of certain examples of the invention shouldnot be used to limit the scope of the present invention. Other examples,features, aspects, embodiments, and advantages of the invention willbecome apparent to those skilled in the art from the followingdescription, which is by way of illustration, one of the best modescontemplated for carrying out the invention. As will be realized, theinvention is capable of other different and obvious aspects, all withoutdeparting from the invention. Accordingly, the drawings and descriptionsshould be regarded as illustrative in nature and not restrictive.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping a handpiece assembly.Thus, an end effector is distal with respect to the more proximalhandpiece assembly. It will be further appreciated that, for convenienceand clarity, spatial terms such as “top” and “bottom” also are usedherein with respect to the clinician gripping the handpiece assembly.However, surgical instruments are used in many orientations andpositions, and these terms are not intended to be limiting and absolute.

It is further understood that any one or more of the teachings,expressions, versions, examples, etc. described herein may be combinedwith any one or more of the other teachings, expressions, versions,examples, etc. that are described herein. The following-describedteachings, expressions, versions, examples, etc. should therefore not beviewed in isolation relative to each other. Various suitable ways inwhich the teachings herein may be combined will be readily apparent tothose skilled in the art in view of the teachings herein. Suchmodifications and variations are intended to be included within thescope of the claims.

I. Exemplary Image Guided Surgery Navigation System

FIG. 1 shows an exemplary IGS navigation system (100) enabling an ENTprocedure to be performed using image guidance. In addition to or inlieu of having the components and operability described herein IGSnavigation system (100) may be constructed and operable in accordancewith at least some of the teachings of U.S. Pat. No. 7,720,521, entitled“Methods and Devices for Performing Procedures within the Ear, Nose,Throat and Paranasal Sinuses,” issued May 18, 2010, the disclosure ofwhich is incorporated by reference herein; and U.S. Pat. Pub. No.2014/0364725, entitled “Systems and Methods for Performing Image GuidedProcedures within the Ear, Nose, Throat and Paranasal Sinuses,”published Dec. 11, 2014, now abandoned, the disclosure of which isincorporated by reference herein.

IGS navigation system (100) of the present example comprises a fieldgenerator assembly (200), which comprises set of magnetic fieldgenerators (206) that are integrated into a horseshoe-shaped frame(204). Field generators (206) are operable to generate alternatingmagnetic fields of different frequencies around the head (H) of thepatient (P). Navigation guidewire (130) may be a standalone device ormay be positioned on an end effector or other location of a medicalinstrument such as a surgical cutting instrument or dilation instrument.In the present example, frame (204) is mounted to a chair (300), withthe patient (P) being seated in the chair (300) such that frame (204) islocated adjacent to the head (H) of the patient (P). By way of exampleonly, chair (300) and/or field generator assembly (200) may beconfigured and operable in accordance with at least some of theteachings of U.S. patent application Ser. No. 15/933,737, entitled“Apparatus to Secure Field Generating Device to Chair,” filed Mar. 23,2018, issued as U.S. Pat. No. 10,561,370 on Feb. 18, 2020, thedisclosure of which is incorporated by reference herein.

IGS navigation system (100) of the present example further comprises aprocessor (110), which controls field generators (206) and otherelements of IGS navigation system (100). For instance, processor (110)is operable to drive field generators (206) to generate alternatingelectromagnetic fields; and process signals from navigation guidewire(130) to determine the location of a sensor in navigation guidewire(130) within the head (H) of the patient (P). Processor (110) comprisesa processing unit communicating with one or more memories. Processor(110) of the present example is mounted in a console (116), whichcomprises operating controls (112) that include a keypad and/or apointing device such as a mouse or trackball. A physician uses operatingcontrols (112) to interact with processor (110) while performing thesurgical procedure.

Navigation guidewire (130) includes a sensor (not shown) that isresponsive to positioning within the alternating magnetic fieldsgenerated by field generators (206). A coupling unit (132) is secured tothe proximal end of navigation guidewire (130) and is configured toprovide communication of data and other signals between console (116)and navigation guidewire (130). In the present example, the sensor ofnavigation guidewire (130) comprises at least one coil at the distal endof navigation guidewire (130). When such a coil is positioned within analternating electromagnetic field generated by field generators (206),the alternating magnetic field may generate electrical current in thecoil, and this electrical current may be communicated along theelectrical conduit(s) in navigation guidewire (130) and further toprocessor (110) via coupling unit (132). This phenomenon may enable IGSnavigation system (100) to determine the location of the distal end ofnavigation guidewire (130) or other medical instrument (e.g., dilationinstrument, surgical cutting instrument, etc.) within athree-dimensional space (i.e., within the head (H) of the patient (P),etc.). To accomplish this, processor (110) executes an algorithm tocalculate location coordinates of the distal end of navigation guidewire(130) from the position related signals of the coil(s) in navigationguidewire (130).

Processor (110) uses software stored in a memory of processor (110) tocalibrate and operate IGS navigation system (100). Such operationincludes driving field generators (206), processing data from navigationguidewire (130), processing data from operating controls (112), anddriving display screen (114). In some implementations, operation mayalso include monitoring and enforcement of one or more safety featuresor functions of IGS navigation system (100). Processor (110) is furtheroperable to provide video in real time via display screen (114), showingthe position of the distal end of navigation guidewire (130) in relationto a video camera image of the patient's head (H), a CT scan image ofthe patient's head (H), and/or a computer generated three-dimensionalmodel of the anatomy within and adjacent to the patient's nasal cavity.Display screen (114) may display such images simultaneously and/orsuperimposed on each other during the surgical procedure. Such displayedimages may also include graphical representations of instruments thatare inserted in the patient's head (H), such as navigation guidewire(130), such that the operator may view the virtual rendering of theinstrument at its actual location in real time. By way of example only,display screen (114) may provide images in accordance with at least someof the teachings of U.S. Pub. No. 2016/0008083, entitled “GuidewireNavigation for Sinuplasty,” published Jan. 14, 2016, issued as U.S. Pat.No. 10,463,242 on Nov. 5, 2019, the disclosure of which is incorporatedby reference herein. In the event that the operator is also using anendoscope, the endoscopic image may also be provided on display screen(114). The images provided through display screen (114) may help guidethe operator in maneuvering and otherwise manipulating instrumentswithin the patient's head (H).

II. Exemplary Interface and Method for Real-Time Camera Placement

It may be advantageous to provide improved interfaces and methods thatallow users additional control and visual context when placing a virtualcamera. A clinician or other user using such interfaces and methods maybe able to place and modify the view of a virtual camera more quicklyand accurately prior to and during a surgical procedure, which mayreduce the need for replacement or adjustment, reduce overall proceduretime, improve patient outcomes, and provide other benefits. As anexample of such a method, FIG. 2 shows an exemplary set of high levelsteps (407) that may be performed by or with a surgery navigation systemsuch as the IGS navigation system (100) to place a virtual camera.

The IGS navigation system (100) may receive (block 400) preoperativeimage data from one or more sources such as a hospital informationsystem or procedure information system where such image data may bestored after it is captured. As has been described, the preoperativeimage data may be used with the IGS navigation system (100) to provideIGS features during a surgical procedure, including a virtual camerapositioned to provide a virtual camera view via a device such as thedisplay (114). The IGS navigation system (100) may provide (block 402) aplacement interface via the display (114) that a clinician may use toprovide inputs defining the virtual camera position and orientation viaan input device such as the operating controls (112). As placementinputs are received (block 404) from the clinician, the IGS navigationsystem (100) will update the placement interface in real-time to provide(block 406) a virtual endoscopic view or preview that may be used by theclinician to preview and provide additional placement inputs prior to aprocedure, to modify placement during performance of a surgicalprocedure, or both.

FIG. 3 shows an exemplary set of steps (408) that may be performed by orwith a surgery navigation system such as the IGS navigation system (100)to provide (block 406) a real-time virtual endoscopic preview duringplacement (block 404) of a virtual camera. This real-time virtualendoscopic preview may be provided via a placement interface, such asthat shown FIGS. 5-9. Those figures show simulated screenshots of anexemplary placement interface (500) that may be provided by a systemperforming steps such as those shown in FIGS. 2-4. The placementinterface (500) of FIG. 5 shows a set of navigation controls (502)operable to navigate through preoperative image sets and adjust avirtual camera view (516), several preoperative image panes including afrontal image (504), a frontal render (514), a side image (510), and atop-down image (512). The placement interface (500) also comprises aperspective indicator (506) for each preoperative image pane showing theperspective from which the preoperative image is being viewed, and acursor (508) that a user may interact with via the operating controls(112) to make selections or other interactions with the placementinterface (500). Varying implementations may have different numbers ofpreoperative image panes within the set of preoperative image panes(e.g., the set of preoperative image panes may comprise one or morepreoperative image panes).

Placement of the virtual camera in the steps of FIG. 3 is achieved byreceiving a set of two inputs from a user that may be used to define afirst point and a second point within the set of preoperative images.Since the set of preoperative images can be used by the IGS navigationsystem (100) to render a 3-D virtual space, the first point and thesecond point can also be interpreted as existing as discrete points in3-D space. In this manner, the first point and the second point can beused to define a virtual camera location (e.g., where one point may beused to define a point along an x, y, and z-axis in the 3-D space atwhich a viewer of the virtual camera view is located) and a virtualcamera orientation (e.g., where the other point may be used to define apoint in 3-D space that a virtual camera positioned at the first pointis facing). It should be understood that, depending upon a particularimplementation, the first point may be the virtual camera's location(e.g., a point at which an observer is viewing from) or the virtualcamera's orientation (e.g., a point that the observer is viewing). Inimplementations where the first point is the virtual camera'sorientation, the second point may be the virtual camera's location, andvice-versa. Some implementations may support multiple selection models,such as where a user may choose to select the points in a desired order.

Returning to FIG. 3, in order to provide the above functionality, as auser interacts with the placement interface (500), the IGS navigationsystem (100) may determine (block 410) a position of the cursor (508)and, if a first point has not been defined (block 412), may render(block 414) a real-time virtual endoscopic preview in the virtual cameraview (516) based upon the position of the cursor over one of thepreoperative images. The real-time virtual endoscopic preview mayinclude depictions of 3-D models of patient anatomy (e.g., which may bebuilt and rendered from pre-operative imaging), may include image slicesand other types of preoperative imaging (e.g., CT image slices, MRIimage slices, ultrasound image slices), or both. In FIG. 5, it can beseen that the virtual camera view (516) is blank. The virtual cameraview may be blank or may show arbitrary image data where the first pointhas not been defined (block 412), and where the cursor (508) is notpositioned within one of the preoperative image panes. As can be seen inFIG. 5, the cursor (508) is positioned at an arbitrary location betweenthe preoperative image panes and the set of navigation controls (502).As a result, when the IGS navigation system (100) attempts to render(block 414) a preview based upon the cursor (508) position, there may beno preview image to show, or an arbitrary preview image.

FIG. 6 shows the placement interface (500) during a first preview, priorto defining (block 412) the first point. Here it can be seen that thevirtual camera view (516) shows a virtual rendered image of an exteriorof a patient's face (518). This is because the cursor (508) is nowpositioned over the frontal image (504). When the IGS navigation system(100) determines (block 410) that the first point has not been defined(block 412), and that the cursor (508) is now positioned over thefrontal image, it may render (block 414) the real-time virtualendoscopic preview based upon the cursor (508) position. Since thecursor (508) is positioned over the frontal image (504), the virtualcamera view (516) shows (block 414) a rendered image (518) having thesame position and orientation as that of the frontal image (504). Thus,if the cursor (508) were positioned over a location on the side image(510) or the top-down image (512), the virtual camera view (516) wouldinstead show a rendered image of the exterior of a patient's face orhead from the side or from above respectively. In this manner, the IGSnavigation system (100) is effectively treating the cursor (508)position on a preoperative image pane as the first point in 3-D space;and the perspective of the frontal image (504) (i.e., as indicated bythe perspective indicator (506)) as the second point in 3-D space, andthen providing the user a preview via the virtual camera view (516) ofthe perspective a user would have from a virtual camera using that firstand second point.

FIG. 7 shows the placement interface (500) during a second preview,after receiving (block 416) a user selection of a location of the cursor(508). When a user selects (block 416) (e.g., by clicking a mouse,keyboard, or other input device associated with the cursor (508)) alocation using the cursor (508), that location may be defined (block418) as the first point (e.g., either the virtual camera's orientationor position). When the first point is defined (block 412), the IGSnavigation system (100) may then render (block 420) a relational previewin the virtual camera view (516) based upon the defined (block 418)first point and the determined (block 410) cursor (508) position. Ratherthan rendering an external view (518) as in FIG. 6, or another view thatrelies on the perspective of the frontal image (504), the IGS navigationsystem (100) may instead use the defined (block 418) first point as thefirst point in 3-D space, and the determined (block 410) cursor positionas the second point in 3-D space when providing the real-time virtualendoscopic preview.

As an example of this, in FIG. 7, it can be seen that the cursor (508)has moved from the location of the defined first point (509). The IGSnavigation system may determine (block 410) the new cursor position, andsince the first point (509) is defined (block 412), may render (block420) the relational preview based upon the first point (509) and usingthe determined (block 410) cursor (508) position as the second point. Asa result, the virtual camera view (516) shows an interior anatomy view(520) that is viewable from the first point (509) when facing thedetermined (block 410) cursor (508) position as the second point. As hasbeen discussed, in implementations where the first point (509) is theorientation, the virtual camera view (516) shows the interior anatomyview (520) that is viewable from a virtual camera positioned at thedetermined (block 410) cursor position, and oriented towards the firstpoint (509). While the described example shows the first point (509) andthe second point being on the same plane (i.e., both are selected ordetermined from the frontal image which depicts a single plane from afixed perspective), it should be understood that the first and secondpoints could be selected from or determined from the cursor (508) beingpositioned on any one or more of the preoperative image panes. Forexample, if the cursor (508) were to be placed over the side image (510)but the first point (509) remained on the frontal image (504), thevirtual camera view (516) would preview a different interior anatomy ofthe patient.

As described above, the rendered (block 420) relational preview shows aview that is dependent upon the relationship of the first and secondpoint in 3-D space. This relational preview may also be dynamicallyrendered, to provide additional visual and spatial context of therelationship between the first and second point. In someimplementations, the virtual camera view (516) may travel along or“fly-through” the line or route formed between the first and secondpoint in 3-D space. This effect is simulated in the virtual camera view(516) in FIGS. 7-9, as it can be seen that the virtual camera view (516)sequentially renders the interior anatomy view (520), followed by afirst progressive interior anatomy view (522), followed by a secondprogressive interior anatomy (524), and so on. Such sequential renderingmay include every intervening preoperative image, or a subset ofintervening preoperative images, and may be rendered at various speedsand framerates as may be desirable. This fly-through effect allows theviewer of the virtual camera view (516) to virtually travel through andview the 3-D space and anatomical structures surrounding the line orroute between the first and second points. In FIGS. 7-9 this isperceived as starting at the first point (509), and then graduallymoving towards the second point (i.e., the determined (block 410) cursorposition in the case of FIG. 7-9), causing the anatomical structuresshown in the interior anatomy view (520) to gradually become closer andmore visible, and in some cases, even passing through those structuresshown in interior anatomy view (520) if the second point is located onthe other side.

While the features and the placement interface (500) are described aboveas displaying a 3-D rendered model of patient anatomy with the virtualcamera view (516) (e.g., the interior anatomy view (520)), it should beunderstood that the same or similar features and interfaces may displayother types of images that may be registered with the IGS navigationsystem (100). This may include, for example, CT image slices, MRI imageslices, and ultrasound image slices. An example is shown in FIGS. 10-13,which depict an alternate placement interface (600), which is shown todisplay images other than 3-D rendered anatomy models. The placementinterface (600) in FIG. 10 includes many of the features of theplacement interface (500) shown in FIG. 7, such as the set of navigationcontrols (502), the frontal image (504), the perspective indicators(506), the side image (510), the top-down image (512), the frontalrender (514), and the virtual camera view (516), having similar featuresand function as described in the context of FIG. 7.

As shown in FIG. 10, a cursor (602) is positioned over the frontal image(504), prior to the first point being defined (block 418). The virtualcamera view (516) displays an image slice (604) (e.g., a CT image slice,MRI image slice, ultrasound image slice, or other image), which may beselected by a user of the system or may be automatically selected uponother factors (e.g., the position of a tracked instrument, the positionof the cursor (602)), for example.

In FIG. 11, the cursor (602) has moved to a new position after thedefinition (block 418) of the first point, and a marker (606) isrendered on the frontal image (504) indicating the defined (block 418)first point. The virtual camera view (516) now displays a portion (608)of an image slice that has been determined and selected from a pluralityof image slices based upon the defined (418) first point and the currentposition of the cursor (602). In this example, since each of the marker(606) and the cursor (602) are present on a single image slice (e.g.,the frontal image (504)), the portion (608) is selected from an imageslice that horizontally intersects the frontal image (504), and isdepicted at various scaled based upon the distance between the cursor(602) and the bone, tissue, or other characteristics depicted in theimage slice that the portion (608) is selected from.

In FIG. 12, the cursor (602) has moved to a subsequent new position,along a y-axis of the frontal image (504) (e.g., the cursor (602) hasmoved vertically upwards while maintaining the same horizontalposition). The portion (608) displayed in FIG. 11 is still visible butis now a subcomponent of a new portion (610) selected from the imageslice based on the cursor's (602) new position relative to the marker(606). Since the cursor (602) has been moved vertically away from themarker (606) the portion (608) is now depicted with a smaller scale,while additional bone and tissue can now be seen in the portion (610).

In FIG. 13, the cursor (602) has moved to a subsequent new position,along an x-axis of the frontal image (504) (e.g., horizontally whilemaintaining the same vertical position). The portion (608) is stilllargely visible, but as a subcomponent of a new portion (612) selectedfrom the image slice based on the cursor's (602) new position relativeto the marker (606). The scale of the portion (612) is unchanged, sincethe cursor (602) did not move vertically along the frontal image (504).As has been described, at any point during movement of the cursor (602)after defining (block 418) the first point a second point may beselected and defined by the system in order to finalize the virtualendoscope configuration. Fly-through viewing may be provided duringconfiguration to aid in placement of the virtual endoscope by displayingfly-through viewing of one or more image slice. This may includedisplaying portions of a single image slice and changing their scalebased upon movements of the cursor (602), may include stepping throughimage slices in sequence in order to provide a variable scale, or both.

In some implementations, the virtual camera view (516) may be configuredto allow users to switch between viewing 3-D modeled anatomy and imageslices, or may display both simultaneously. Whether the virtual cameraview (516) displays 3-D modeled anatomy or image slices, the additionalcontext provided by a fly-through viewing of the 3-D space surroundingthe line between the first and second point may provide valuable visualcontext to a clinician configuring a virtual camera, as it may revealthat the virtual camera's potential position and orientation will resultin a non-targeted anatomical structure blocking visibility of animportant area of the surgical site, that the important area is notactually located between or around the line formed by the first andsecond point; or that the important area of the surgical site may bebetter viewed from a different first point, for example. If this is thecase, the clinician may move the cursor (508) to a separate location inthe preoperative image panes in order to cause the IGS navigation system(100) to determine (block 410) the new cursor (508) position and render(block 420) an updated relational preview based upon the new position,in real-time. While the descriptions of FIG. 3 describe rendering (block414) a preview prior to a user selecting a first point and rendering(block 420) a relational preview prior to a user selecting a secondpoint, it should understand that various implementations of thedescribed interface and method may include one or both previews. Forexample, some implementations may only render (block 420) the relationalpreview, with the virtual camera view (block 416) being blank or showingarbitrary or other image data prior to the first point being defined(block 412).

Where the clinician is satisfied with the current placement of thevirtual camera at the first point (509), and orientation of the virtualcamera towards the current location of the cursor (508) based upon theflythrough preview of the interior anatomy view, the IGS navigationsystem (100) may receive (522) a second user selection and define (block424) the second point based thereon. With the first point defined (block412) and the second point defined (block 422), the virtual camera view(516) may continue to show the most recent rendered (block 420)relational preview or other images to allow the clinician to review(block 426) and confirm the virtual camera placement and orientationbefore finalizing and generating a virtual camera definition that may beused by the IGS navigation system (100) during a surgical procedure.

FIG. 4 shows an exemplary set of steps (427) that may be performed by orwith a surgery navigation system such as the IGS navigation system (100)to review, modify, and confirm placement of a virtual camera. Prior toconfirming (block 428) the virtual camera placement and orientation, thecursor (508) or other user inputs may be used to interact with the setof navigation controls (502) or other use inputs to control the rendered(block 420) relational preview if the clinician wishes to, for example,control the speed of the flythrough or pause the flythrough at variouspoints to aid in review. Based on user inputs, the areas surrounding theflythrough may be navigated (block 436) by repositioning the cameraalong the route, or by changing the orientation of the camera along theroute. For example, a clinician might see something of concern in theflythrough, and may pause the preview, move the virtual camera off theflythrough route and through 3-D space to a separate point along one ormore of the X, Y, and Z axis, and then rotate the orientation of thecamera upwards to view something above and to the side of the flythroughroute in more detail.

A user selection during such navigation (block 436) may cause one ormore of the first point or the second point to be redefined to newlocations. For example, a user selection of a location of the virtualcamera view (516) may cause one or more of the first point and thesecond point to be redefined. As another example, one or more of thepreoperative image panes may be updated in real-time during suchnavigation (block 436) to display particular preoperative imagesassociated with the 3-D space in which the virtual camera view (516) iscurrently positioned or facing, such that a subsequent selection orcursor (508) navigation of the newly updated preoperative image pane maycause one or more of the first point and the second point to beredefined based thereon.

Other features that may be available to a user prior to confirming(block 428) placement and orientation of the virtual camera may includediscarding and re-defining (block 432) the first point or the secondpoint, and swapping (block 434) the first and second point. In somecases after viewing the relational flythrough, the clinician maydetermine that either of the selected points does not provide thedesired virtual endoscopic view of the surgical site. In such a case,one or both defined points may be discarded, returning the clinician tothe appropriate placement interface (500) state and step of FIG. 3.

Swapping (block 434) the first and second points (i.e., using the secondpoint as the position of the virtual camera, and using the first pointas the orientation of the virtual camera) may be activated by aclinician based upon one or more user inputs. It may be advantageous toprovide such functionality with a single click, such that a clinicianmay view an initially rendered relational preview, swap (block 434) thepoints and view the preview in reverse to determine if it provides amore desirable view, and then swap (block 434) again to return to theoriginal if it does not.

Improving the usability and simplicity of interfaces such as theplacement interface (500) provides numerous advantages to users. Thedisclosed interfaces and methods can reduce placement of a virtualcamera in 3-D operative image space to a small number of mouse clicks,keyboard presses, or other inputs. For example, in some scenarios, aclinician or other user may be able to place and orient a virtual camerawith as few as two selection inputs (e.g., a first selection (block 416)or mouse click to define (block 418) the first point, a second selection(block 422) or mouse click to define (block 424) the second point) andone navigational input (e.g., positioning a cursor over a location on apreoperative image). The automated real-time flythrough preview removesthe need for additional selection inputs (e.g., manually navigatingalong a similar route by clicking a mouse on buttons of the set ofnavigation controls (502) to place, review, and confirm virtual cameralocation and orientation). This may be advantageous in that it bothreduces the time requires to configure the virtual camera, and in thatit reduces both the number of and complexity of interactions (e.g.,mouse, keyboard, or other input selections) that the clinician has withinterface and the operating controls (112), which may be beneficial inmaintaining a sterile environment in addition to other benefits.

After receiving confirmation (block 428) of the placement andorientation of the virtual camera, the IGS navigation system (100) mayfinalize placement by saving the first and second point and otherassociated data produced during the steps of FIGS. 2-4 into a virtualcamera definition or other configuration set so that the virtual cameramay be automatically repositioned in the future in order to provide(block 430) the desired virtual endoscopic view during an associatedsurgical procedure.

Variations on the systems, methods, and interfaces described above existand will be apparent to one of ordinary skill in the art in light ofthis disclosure. For example, while some of the above discussion hasdescribed the first point as being the virtual camera's location, itshould be understood that in some implementations the first point may bethe virtual camera's orientation. This may be advantageous where aclinician has determined a position within the surgical area that is ofinterest and wishes to select that as the point of orientation (i.e.,the second point), then preview a number of camera positions (e.g., thefirst point) using the real-time virtual endoscopic preview andrelational flythrough before making a selection. Choosing the virtualcamera's location as the first point may be advantageous where aclinician may use their experience to first determine the best locationfor the virtual camera, and then may use the real-time virtualendoscopic preview and relational flythrough to choose a point of thesurgical area that they would like to focus the virtual camera upon.

III. Exemplary Combinations

The following examples relate to various non-exhaustive ways in whichthe teachings herein may be combined or applied. It should be understoodthat the following examples are not intended to restrict the coverage ofany claims that may be presented at any time in this application or insubsequent filings of this application. No disclaimer is intended. Thefollowing examples are being provided for nothing more than merelyillustrative purposes. It is contemplated that the various teachingsherein may be arranged and applied in numerous other ways. It is alsocontemplated that some variations may omit certain features referred toin the below examples. Therefore, none of the aspects or featuresreferred to below should be deemed critical unless otherwise explicitlyindicated as such at a later date by the inventors or by a successor ininterest to the inventors. If any claims are presented in thisapplication or in subsequent filings related to this application thatinclude additional features beyond those referred to below, thoseadditional features shall not be presumed to have been added for anyreason relating to patentability.

Example 1

A system comprising: (a) a display; (b) a user input; (c) a set ofpreoperative images; and (d) a processor configured to provide a virtualcamera placement interface to a user via the display and receive inputsvia the user input the virtual camera placement interface comprising aset of preoperative image panes and a virtual camera view, wherein eachof the set of preoperative image panes comprises a preoperative imagefrom the set of preoperative images, and wherein the user input isoperable to move a cursor over and make selections from the set ofpreoperative image panes, wherein the processor is further configuredto: (i) define a first point based upon a first selection received viathe user input, wherein the first selection comprises a point on one ofthe set of preoperative image panes, (ii) define a second point basedupon a cursor position of the cursor on one of the set of preoperativeimage panes, and (iii) display a real-time virtual endoscopic preview inthe virtual camera view based upon the first point and the second point.

Example 2

The system of Example 1, wherein the processor is further configured to:(i) change the value of the second point as the cursor moves and thecursor position changes, and (ii) update the real-time virtualendoscopic preview as the second point is changed.

Example 3

The system of any one or more of Examples 1 through 2, wherein theprocessor is further configured to: (i) after displaying the real-timevirtual endoscopic preview, receive a second selection via the userinput, wherein the second selection comprises a selected second pointdetermined based upon the second point, and (ii) create a virtual cameradefinition based upon the first point and the selected second point,wherein the virtual camera definition is configured to be usable by animage guided surgery navigation system to produce a virtual endoscopicview during a surgical procedure.

Example 4

The system of Example 3, wherein the system comprises the image guidedsurgery navigation system, and wherein the user input comprises apointing device.

Example 5

The system of any one or more of Examples 1 through 4, wherein theprocessor is further configured to, when displaying the real-timevirtual endoscopic preview: (i) determine a spatial relationship betweenthe first point and the second point, (ii) create a route through theset of preoperative images based upon the spatial relationship, and(iii) display a sequence of flythrough images in the virtual camera viewbased upon the route.

Example 6

The system of Example 5, wherein the sequence of flythrough imagescomprises a plurality of sequential images selected from the set ofpreoperative images and arranged in the order that they would be viewedwhile traversing the route.

Example 7

The system of any one or more Examples 5 through 6, wherein the virtualcamera placement interface comprises a set of navigation controls, andwherein the processor is further configured to, in response to inputsvia the set of navigation controls, adjust the speed and order at whichthe sequence of flythrough images is displayed.

Example 8

The system of Example 7, wherein the processor is further configured to,in response to inputs via the set of navigations controls: (i) pause thesequence of flythrough images, (ii) display a new image from the set ofpreoperative images in the virtual camera view based upon inputsindicating a change to one or both of the view position and orientationfrom an initial view position and orientation provided by the route, and(iii) change the value of one or both of the first point and the secondpoint based upon the new image.

Example 9

The system of Example 8, wherein the processor is further configured to,when the new image is displayed, update one or more of the preoperativeimage panes to comprise a new preoperative image from the set ofpreoperative images, wherein the new preoperative image for each isdetermined based upon its proximity and relationship to the new image.

Example 10

The system of any one or more of Examples 5-9, wherein the first pointis associated with a location of a virtual camera and the second pointis associated with an orientation of the virtual camera, and wherein theroute comprises a start point based that is determined based upon thefirst point and an end point that is determined based upon the secondpoint.

Example 11

The system of any one or more of Examples 5-10, wherein the second pointis associated with a location of a virtual camera and the first point isassociated with an orientation of the virtual camera, and wherein theroute comprises a start point based that is determined based upon thesecond point and an end point that is determined based upon the firstpoint.

Example 12

The system of any one or more of Examples 1-11, wherein the processor isfurther configured to: (i) after displaying the real-time virtualendoscopic preview, receive a second selection via the user input,wherein the second selection comprises a selected second pointdetermined based upon the second point, (ii) based upon a swap selectionreceived via the user input, swap the values of the first point and theselected second point, and (iii) display the real-time virtualendoscopic preview in the virtual camera view based upon the changedvalues of the first point and the selected second point.

Example 13

The system of any one or more of Examples 1 through 12, wherein theprocessor is further configured to: (i) after displaying the real-timevirtual endoscopic preview, receive a second selection via the userinput, wherein the second selection comprises a selected second pointdetermined based upon the second point, (ii) based upon a modifyselection received via the user input, discard the selected value of oneof the first point or the selected second point, (iii) define a modifiedpoint based upon the cursor position, wherein the modified point is thepoint whose value was discarded, and (iv) display the real-time virtualendoscopic preview in the virtual camera view based upon a retainedpoint and the modified point, wherein the retained point is the pointwhose value was not discarded.

Example 14

The system of any one or more of Examples 1 through 14, wherein theprocessor is further configured to, prior to the first selection beingreceived via the user input: (i) define the first point based upon thecursor position on one of the set of preoperative image panes, whereinthat preoperative image pane is associated with a preoperative image ofthe set of preoperative images, and wherein the preoperative imagecomprises a perspective indicating an orientation from which thepreoperative image is viewed, (ii) define the second point based uponthe perspective of the preoperative image, and (iii) display thereal-time virtual endoscopic preview in the virtual camera view basedupon the first point and the second point.

Example 15

A method for configuring a virtual camera in 3-D space with a virtualcamera placement interface, comprising the steps: (a) displaying a setof preoperative image panes via the virtual camera placement interface,wherein each of the set of preoperative image panes comprises apreoperative image from a set of preoperative images associated with apatient; (b) defining a first point based upon receiving a firstselection from a user via the virtual camera placement interface,wherein the first selection comprises a point on one of the set ofpreoperative image panes; (c) defining a second point based upon acursor position of a cursor on one of the set of preoperative imagepanes; (d) displaying a real-time virtual endoscopic preview via thevirtual camera placement interface based upon the first point and thesecond point; and (e) changing the value of the second point as thecursor is moved by the user and the cursor position changes.

Example 16

The method of Example 15, further comprising the steps: (a) afterdisplaying the real-time virtual endoscopic preview, receiving a secondselection from the user via the virtual camera placement interface,wherein the second selection comprises a selected third point based uponthe second point; and (b) creating a virtual camera definition basedupon the first point and the selected third point, wherein the virtualcamera definition is configured to be usable by an image guided surgerynavigation system to produce a virtual endoscopic view during thesurgical procedure.

Example 17

The method of Example 16, wherein the first selection is the onlyselection input received from the user prior to displaying the real-timevirtual endoscopic preview; and wherein the second selection is the onlyselection input received from the user after receiving the firstselection and prior to creating the virtual camera definition.

Example 18

The method of any one or more of Examples 15-17, further comprising thesteps: (a) determining a spatial relationship between the first pointand the second point, (b) creating a route through the set ofpreoperative images based upon the spatial relationship, and (c)displaying a sequence of flythrough images via the virtual cameraplacement interface based upon the route.

Example 19

The method of Example 18, wherein the sequence of flythrough imagescomprise a plurality of sequential images selected from the set ofpreoperative images and arranged in the order that they would be viewedwhile traversing the route.

Example 20

A system comprising: (a) a display; (b) a user input; (c) a set ofpreoperative images; and (d) a processor configured to provide a virtualcamera placement interface to a user via the display and receive inputsvia the user input, the virtual camera placement interface comprising aset of preoperative image panes and a virtual camera view, wherein eachof the set of preoperative image panes comprises a preoperative imagefrom the set of preoperative images, and wherein the user input isoperable to move a cursor over and make selections from the set ofpreoperative image panes, wherein the processor is further configuredto: (i) define a static point based upon a first selection received viathe user input, wherein the first selection comprises a point on one ofthe set of preoperative image panes, (ii) define a dynamic point basedupon a cursor position of the cursor on one of the set of preoperativeimage panes, (iii) display a real-time virtual endoscopic preview in thevirtual camera view based upon the static point and the dynamic point,(iv) after displaying the real-time virtual endoscopic preview, receivea second selection via the user input and define a second static pointbased upon the second selection, wherein the second selection comprisesthe dynamic point, and (v) create a virtual camera definition based uponthe static point and the second static point, wherein the virtual cameradefinition is configured to be usable by an image guided surgerynavigation system to produce a virtual endoscopic view during a surgicalprocedure.

IV. Miscellaneous

It should be understood that any of the examples described herein mayinclude various other features in addition to or in lieu of thosedescribed above. By way of example only, any of the examples describedherein may also include one or more of the various features disclosed inany of the various references that are incorporated by reference herein.

It should be understood that any one or more of the teachings,expressions, embodiments, examples, etc. described herein may becombined with any one or more of the other teachings, expressions,embodiments, examples, etc. that are described herein. Theabove-described teachings, expressions, embodiments, examples, etc.should therefore not be viewed in isolation relative to each other.Various suitable ways in which the teachings herein may be combined willbe readily apparent to those skilled in the art in view of the teachingsherein. Such modifications and variations are intended to be includedwithin the scope of the claims.

It should be appreciated that any patent, publication, or otherdisclosure material, in whole or in part, that is said to beincorporated by reference herein is incorporated herein only to theextent that the incorporated material does not conflict with existingdefinitions, statements, or other disclosure material set forth in thisdisclosure. As such, and to the extent necessary, the disclosure asexplicitly set forth herein supersedes any conflicting materialincorporated herein by reference. Any material, or portion thereof, thatis said to be incorporated by reference herein, but which conflicts withexisting definitions, statements, or other disclosure material set forthherein will only be incorporated to the extent that no conflict arisesbetween that incorporated material and the existing disclosure material.

Versions of the devices disclosed herein can be designed to be disposedof after a single use, or they can be designed to be used multipletimes. Versions may, in either or both cases, be reconditioned for reuseafter at least one use. Reconditioning may include any combination ofthe steps of disassembly of the device, followed by cleaning orreplacement of particular pieces, and subsequent reassembly. Inparticular, versions of the device may be disassembled, and any numberof the particular pieces or parts of the device may be selectivelyreplaced or removed in any combination. Upon cleaning and/or replacementof particular parts, versions of the device may be reassembled forsubsequent use either at a reconditioning facility, or by a surgicalteam immediately prior to a surgical procedure. Those skilled in the artwill appreciate that reconditioning of a device may utilize a variety oftechniques for disassembly, cleaning/replacement, and reassembly. Use ofsuch techniques, and the resulting reconditioned device, are all withinthe scope of the present application.

By way of example only, versions described herein may be processedbefore surgery. First, a new or used instrument may be obtained and ifnecessary cleaned. The instrument may then be sterilized. In onesterilization technique, the instrument is placed in a closed and sealedcontainer, such as a plastic or TYVEK bag. The container and instrumentmay then be placed in a field of radiation that can penetrate thecontainer, such as gamma radiation, x-rays, or high-energy electrons.The radiation may kill bacteria on the instrument and in the container.The sterilized instrument may then be stored in the sterile container.The sealed container may keep the instrument sterile until it is openedin a surgical facility. A device may also be sterilized using any othertechnique known in the art, including but not limited to beta or gammaradiation, ethylene oxide, or steam.

Having shown and described various versions of the present invention,further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications by one skilled in the artwithout departing from the scope of the present invention. Several ofsuch potential modifications have been mentioned, and others will beapparent to those skilled in the art. For instance, the examples,versions, geometrics, materials, dimensions, ratios, steps, and the likediscussed above are illustrative and are not required. Accordingly, thescope of the present invention should be considered in terms of thefollowing claims and is understood not to be limited to the details ofstructure and operation shown and described in the specification anddrawings.

We claim:
 1. A system comprising: (a) a display; (b) user input; (c) aset of preoperative images associated with a patient; and (d) aprocessor configured to provide a virtual camera placement interface toa user via the display and receive inputs via the user input; whereinthe virtual camera placement interface comprises a set of preoperativeimage panes and a virtual camera view, wherein each of the set ofpreoperative image panes corresponds to a viewpoint, wherein the set ofpreoperative image panes comprises preoperative image panescorresponding to a top-down viewpoint, a side viewpoint, and a frontalviewpoint, wherein each of the set of preoperative image panes comprisesa preoperative image from the set of preoperative images displayed fromthe viewpoint corresponding to the preoperative image pane whichcomprises it, and wherein the user input is operable to move a cursorover and make selections from the set of preoperative image panes,wherein the processor is further configured to: (i) define a first pointbased upon a first selection received via the user input, wherein thefirst selection comprises a point on one of the set of preoperativeimage panes that corresponds to a first cursor position of the cursorwhen the first selection is received and is based upon the viewpointcorresponding to the preoperative image pane comprising the pointcorresponding to the first cursor position of the cursor when the firstselection is received, (ii) define a second point based upon (A) asecond cursor position of the cursor located on any of the set ofpreoperative image panes, and (B) the viewpoint corresponding to thepreoperative image pane on which the second cursor position is located,and (iii) display a real-time virtual endoscopic preview in the virtualcamera view based upon the first point and the second point.
 2. Thesystem of claim 1, wherein the processor is further configured to: (i)change the value of the second point as the cursor moves and the secondcursor position changes, and (ii) update the real-time virtualendoscopic preview as the second point is changed.
 3. The system ofclaim 1, wherein the processor is further configured to: (i) afterdisplaying the real-time virtual endoscopic preview, receive a secondselection via the user input, wherein the second selection comprises aselected second point determined based upon the second point, and (ii)create a virtual camera definition based upon the first point and theselected second point, wherein the virtual camera definition isconfigured to be usable by an image guided surgery navigation system toproduce a virtual endoscopic view during a surgical procedure.
 4. Thesystem of claim 3, wherein the system comprises the image guided surgerynavigation system, and wherein the user input comprises a pointingdevice.
 5. The system of claim 1, wherein the processor is furtherconfigured to, when displaying the real-time virtual endoscopic preview:(i) determine a spatial relationship between the first point and thesecond point, (ii) create a route through the set of preoperative imagesbased upon the spatial relationship, and (iii) display a sequence offlythrough images in the virtual camera view based upon the route. 6.The system of claim 5, wherein the sequence of flythrough imagescomprises a plurality of sequential images selected from the set ofpreoperative images and arranged in the order that they would be viewedwhile traversing the route.
 7. The system of claim 5, wherein thevirtual camera placement interface comprises a set of navigationcontrols, and wherein the processor is further configured to, inresponse to inputs via the set of navigation controls, adjust the speedand order at which the sequence of flythrough images is displayed. 8.The system of claim 7, wherein the processor is further configured to,in response to inputs via the set of navigations controls: (i) pausedisplay of the sequence of flythrough images, (ii) display a new imagefrom the set of preoperative images in the virtual camera view basedupon inputs indicating a change to one or both of the view position andorientation from an initial view position and orientation provided bythe route, and (iii) change the value of one or both of the first pointand the second point based upon the new image.
 9. The system of claim 8,wherein the processor is further configured to, when the new image isdisplayed, update one or more of the preoperative image panes tocomprise a new preoperative image from the set of preoperative images,wherein the new preoperative image for each is determined based upon itsproximity and relationship to the new image.
 10. The system of claim 5,wherein the first point is associated with a location of a virtualcamera and the second point is associated with an orientation of thevirtual camera, and wherein the route comprises a start point that isdetermined based upon the first point and an end point that isdetermined based upon the second point.
 11. The system of claim 5,wherein the second point is associated with a location of a virtualcamera and the first point is associated with an orientation of thevirtual camera, and wherein the route comprises a start point that isdetermined based upon the second point and an end point that isdetermined based upon the first point.
 12. The system of claim 1,wherein the processor is further configured to: (i) after displaying thereal-time virtual endoscopic preview, receive a second selection via theuser input, wherein the second selection comprises a selected secondpoint determined based upon the second point, (ii) display the real-timevirtual endoscopic preview in the virtual camera view based on a virtualcamera located at the first point and oriented toward the selectedsecond point, (iii) based upon a swap selection received via the userinput, swap the values of the first point and the selected second point,and (iv) display the real-time virtual endoscopic preview in the virtualcamera view based upon a virtual camera located at the changed firstpoint and oriented toward the changed selected second point.
 13. Thesystem of claim 1, wherein the processor is further configured to: (i)after displaying the real-time virtual endoscopic preview, receive asecond selection via the user input, wherein the second selectioncomprises a selected second point determined based upon the secondpoint, (ii) based upon a modify selection received via the user input,discard the selected value of one of the first point or the selectedsecond point, (iii) define a modified point based upon a third cursorposition, wherein the modified point is the point whose value wasdiscarded, and (iv) display the real-time virtual endoscopic preview inthe virtual camera view based upon a retained point and the modifiedpoint, wherein the retained point is the point whose value was notdiscarded.
 14. The system of claim 1, wherein the processor is furtherconfigured to, prior to the first selection being received via the userinput: (i) define the first point based upon the first cursor positionlocated on one of the set of preoperative image panes, (ii) define thesecond point based upon the viewpoint corresponding to the preoperativeimage pane on which the first cursor position is located, and (iii)display the real-time virtual endoscopic preview in the virtual cameraview based upon the first point and the second point.
 15. A method forconfiguring a virtual camera in 3-D space with a virtual cameraplacement interface, comprising the steps: (a) displaying a set ofpreoperative image panes via the virtual camera placement interface,wherein each of the set of preoperative image panes corresponds to aviewpoint, wherein the set of preoperative image panes comprisespreoperative image panes corresponding to a top-down viewpoint, a sideviewpoint, and a frontal viewpoint, wherein each of the set ofpreoperative image panes comprises a preoperative image from a set ofpreoperative images associated with a patient displayed from theviewpoint corresponding to the preoperative image pane which comprisesit; (b) defining a first point based upon receiving a first selectionfrom a user via the virtual camera placement interface, wherein thefirst selection comprises a point on one of the set of preoperativeimage panes that corresponds to a first cursor position of a cursorpositioned by the user over that preoperative image pane and is basedupon the viewpoint corresponding to that preoperative image pane; (c)defining a second point based upon (i) a second cursor position of thecursor located on any of the set of preoperative image panes, and (ii)the viewpoint corresponding to the preoperative image pane on which thesecond cursor position is located; (d) displaying a real-time virtualendoscopic preview via the virtual camera placement interface based uponthe first point and the second point; and (e) changing the value of thesecond point as the cursor is moved by the user and the second cursorposition changes.
 16. The method of claim 15, further comprising thesteps: (a) after displaying the real-time virtual endoscopic preview,receiving a second selection from the user via the virtual cameraplacement interface, wherein the second selection comprises a selectedthird point based upon the second point; and (b) creating a virtualcamera definition based upon the first point and the selected thirdpoint, wherein the virtual camera definition is configured to be usableby an image guided surgery navigation system to produce a virtualendoscopic view during a surgical procedure.
 17. The method of claim 16,wherein the first selection is the only selection input received fromthe user prior to displaying the real-time virtual endoscopic preview;and wherein the second selection is the only selection input receivedfrom the user after receiving the first selection and prior to creatingthe virtual camera definition.
 18. The method of claim 15, furthercomprising the steps: (a) determining a spatial relationship between thefirst point and the second point; (b) creating a route through the setof preoperative images based upon the spatial relationship; and (c)displaying a sequence of flythrough images via the virtual cameraplacement interface based upon the route.
 19. The method of claim 18,wherein the sequence of flythrough images comprise a plurality ofsequential images selected from the set of preoperative images andarranged in the order that they would be viewed while traversing theroute.
 20. A system comprising: (a) a display; (b) user input; (c) a setof preoperative images associated with a patient; and (d) a processorconfigured to provide a virtual camera placement interface to a user viathe display and receive inputs via the user input; the virtual cameraplacement interface comprising a set of preoperative image panes and avirtual camera view, wherein each of the set of preoperative image panescomprises a preoperative image from the set of preoperative images, andwherein the user input is operable to move a cursor over and makeselections from the set of preoperative image panes, wherein theprocessor is further configured to: (i) define a first point based upona first selection received via the user input, wherein the firstselection comprises a point on one of the set of preoperative imagepanes, (ii) define a second point based upon a cursor position of thecursor on one of the set of preoperative image panes, (iii) display areal-time virtual endoscopic preview in the virtual camera view basedupon the first point and the second point, (iv) receive a secondselection via the user input, wherein the second selection comprises aselected second point determined based upon the second point, (v) basedupon a modify selection received via the user input, discard theselected value of one of the first point or the selected second point,(vi) define a modified point based upon the cursor position, wherein themodified point is the point whose value was discarded, and (vii) displaythe real-time virtual endoscopic preview in the virtual camera viewbased upon a retained point and the modified point, wherein the retainedpoint is the point whose value was not discarded.